Volume 618, October 2018
|Number of page(s)||22|
|Section||Interstellar and circumstellar matter|
|Published online||11 October 2018|
Core fragmentation and Toomre stability analysis of W3(H2O)
Max Planck Institute for Astronomy,
2 International Max Planck Research School for Astronomy and Cosmic Physics at the University of Heidelberg (IMPRS-HD)
3 IRAM, 300 Rue de la Piscine, Domaine Universitaire de Grenoble, 38406 St.-Martin-d’Hères, France
4 Institute of Astronomy and Astrophysics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
5 Department of Physics and Astronomy, McMaster University, 1280 Main St. W, Hamilton, ON L8S 4M1, Canada
6 I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany
7 Harvard-Smithsonian Center for Astrophysics, 160 Garden St, Cambridge, MA 02420, USA
8 INAF, Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
9 Laboratoire d’Astrophysique de Bordeaux – UMR 5804, CNRS – Université Bordeaux 1, BP 89, 33270 Floirac, France
10 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
11 Max-Planck-Institut für Extraterrestrische Physik, Gissenbachstrasse 1, 85748 Garching, Germany
12 Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autonóma de México, PO Box 3-72, 58090 Morelia, Michoacan, Mexico
13 School of Physics & Astronomy, E.C. Stoner Building, The University of Leeds, Leeds LS2 9JT, UK
14 UK Astronomy Technology Centre, Royal Observatory Edinburgh, Blackford Hill, Edinburgh EH9 3HJ, UK
15 INAF – Osservatorio Astronomico di Cagliari, Via della Scienza 5, Selargius CA 09047, Italy
16 Astrophysics Research Institute, Liverpool John Moores University, 146 Brownlow Hill, Liverpool L3 5RF, UK
17 Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
18 CNRS, Institut de Planétologie et d’Astrophysique de Grenoble, Université Grenoble Alpes, 38000 Grenoble, France
19 Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85748 Garching, Germany
20 School of Physics and Astronomy, Cardiff University, Cardiff CF24 3AA, UK
21 Centre for Astrophysics and Planetary Science, University of Kent, Canterbury CT2 7NH, UK
22 SOFIA Science Center, Deutsches SOFIA Institut, NASA Ames Research Center, Moffett Field, CA 94035, USA
23 Universidad Autónoma de Chile, Av. Pedro de Valdivia 425, Santiago, Chile
Accepted: 21 July 2018
Context. The fragmentation mode of high-mass molecular clumps and the properties of the central rotating structures surrounding the most luminous objects have yet to be comprehensively characterised.
Aims. We study the fragmentation and kinematics of the high-mass star-forming region W3(H2O), as part of the IRAM NOrthern Extended Millimeter Array (NOEMA) large programme CORE.
Methods. Using the IRAM NOEMA and the IRAM 30 m telescope, the CORE survey has obtained high-resolution observations of 20 well-known highly luminous star-forming regions in the 1.37 mm wavelength regime in both line and dust continuum emission.
Results. We present the spectral line setup of the CORE survey and a case study for W3(H2O). At ~0.′′35 (700 AU at 2.0 kpc) resolution, the W3(H2O) clump fragments into two cores (west and east), separated by ~2300 AU. Velocity shifts of a few km s−1 are observed in the dense-gas tracer, CH3CN, across both cores, consistent with rotation and perpendicular to the directions of two bipolar outflows, one emanating from each core. The kinematics of the rotating structure about W3(H2O) W shows signs of differential rotation of material, possibly in a disk-like object. The observed rotational signature around W3(H2O) E may be due to a disk-like object, an unresolved binary (or multiple) system, or a combination of both. We fit the emission of CH3CN (12K−11K), K = 4−6 and derive a gas temperature map with a median temperature of ~165 K across W3(H2O). We create a Toomre Q map to study thestability of the rotating structures against gravitational instability. The rotating structures appear to be Toomre unstable close to their outer boundaries, with a possibility of further fragmentation in the differentially rotating core, W3(H2O) W. Rapid cooling in the Toomre unstable regions supports the fragmentation scenario.
Conclusions. Combining millimetre dust continuum and spectral line data toward the famous high-mass star-forming region W3(H2O), we identify core fragmentation on large scales, and indications for possible disk fragmentation on smaller spatial scales.
Key words: stars: formation / stars: massive / stars: early-type / stars: kinematics and dynamics / stars: individual: W3(H2O)/(OH) / techniques: interferometric
Based on observations from an IRAM large program. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain).
Observational data are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (220.127.116.11) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/618/A46, or alternatively at http://www.mpia.de/core.
© ESO 2018
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